Vets say the illness is unlike any other, five dogs killed since January. Dogs develop cough and breathing problems, can develop into pneumonia

A dog flu epidemic has broken out in Chicago.Five canines have died and more than 1,000 have been treated for the infection which was first detected in January.

Dog owners have been warned to avoid parks, group pet training, and doggy day care centers to protect their animals. According to a vet working to tackle the crisis, Dr Jerry Klein, dogs can be infectious without showing symptoms.

Like kennel cough - a less serious illness - dog flu can be infectious for up to a week after symptoms subside. Dr Klein told WBBM-TV: 'I've been here for 35 years, it's probably the worst type of outbreak I've ever experienced.'

Flu-stricken dogs develop a cough and breathing problems. They are treated with oxygen masks and ventilator tanks. In the worst cases, the illness develops into life-threatening pneumonia.